This invention relates to a dock leveler used to bridge the gap between a loading dock and the bed of a truck or carrier parked adjacent the loading dock, and more particularly to improvements in dock levelers incorporating an airbag or other inflatable member for raising the ramp of the dock leveler.
A dock leveler typically includes a frame or supporting structure mounted in a pit or depression in the loading dock. The rear end of a ramp or deck plate is pivotally mounted to the supporting structure so that the ramp is movable between an inclined position in which the ramp is supported by the truck bed, a horizontal inoperative position, and a raised position in which the forward end of the ramp is raised above the truck bed.
An extension lip is pivotally mounted to the forward end of the ramp, and is movable between a downwardly hanging pendant position and an extended position in which the lip forms an extension to the ramp.
After a truck has parked in front of the loading dock in preparation for a loading or unloading operation, the ramp of the dock leveler is raised to its upwardly inclined position. As the ramp is lowered, the lip is pivoted outwardly to its extended position. As the ramp is subsequently lowered, the lip engages the bed of the truck to support the ramp, such that the ramp and the lip in combination bridge the gap between the loading dock and the truck bed. After the loading or unloading operation is completed, the ramp is raised and the lip falls by gravity to its pendant position. The ramp is then lowered to its horizontal position, and the truck can then pull away from the loading dock.
In the past, the ramp has been pivoted to its upward position in response to operation of a mechanical or hydraulic mechanism. However, recent developments in the dock leveler art disclose an inflatable member or bag utilized to pivot the ramp to its upwardly inclined position. These applications disclose a bag inflated with low pressure air by an inflating device such as a fan or blower, and are hereby incorporated by reference in their entirety.
It has been found that certain problems can occur when incorporating an inflatable member into a dock leveler. For example, if the inflatable bag directly interconnects the floor of the pit with the pivoting ramp, the bag can sometimes tear away from its interconnection with the ramp. Further the long distance between the pit floor and the ramp can cause lateral instability of the bag assembly.
The present invention relates to improvements to the above-noted dock levelers incorporating an inflatable member. In one aspect, the dock leveler of the present invention is adapted to be mounted to a loading dock, and includes a ramp having a rear edge movably interconnected with the loading dock, an intermediate member movable relative to the ramp, and an inflatable assembly (e.g., one or more inflatable bags) positioned to cause relative movement between the ramp and the intermediate member to thereby result in movement of the ramp relative to the loading dock. The utilization of an intermediate member has been found to improve the dock leveler by maintaining the ends of the inflatable assembly in a closer, more controlled area.
In one embodiment, the loading dock includes a pit having a pit floor. The intermediate member can be movably (e.g., pivotally) mounted to either a pit floor, the ramp, or some other location on the loading dock. In another embodiment, the dock leveler further includes a linkage member interconnecting the intermediate member with the ramp. In yet another embodiment, a roller member is mounted to an end of the intermediate member. The inflatable assembly can include either a blower device or a vacuum device.
In another aspect, the present invention is embodied in a dock leveler including a ramp having a rear edge movably interconnected with the loading dock, an inflatable assembly operatively interconnected with the ramp, and a vacuum device operatively associated with the inflatable assembly for selectively removing gas from the inflatable assembly to cause movement of the ramp. The vacuum device can be mounted to a vacuum support (e.g., rigidly secured to the loading dock), and an intermediate member movably mounted relative to the vacuum support. In this embodiment, the inflatable assembly can be operatively positioned between the vacuum support and the intermediate member.
The present invention is also embodied in a method of operating a dock leveler having a pivotally-mounted ramp, an intermediate member movable relative to the ramp, and an inflatable assembly positioned to cause relative movement between the ramp and the intermediate member upon inflation of the inflatable member. The method includes the steps of inflating the inflatable member, and moving (e.g., pivoting) the intermediate member relative to the ramp to thereby pivot (e.g., raise or lower) the ramp. Movement of an intermediate member to cause movement of the ramp has been found to improve the dock leveler by maintaining the ends of the inflatable assembly in a closer, more controlled area.
In one embodiment, the dock leveler further includes a linkage member interconnecting the intermediate member with the ramp, and the step of moving the intermediate member includes the step of moving the linkage member. In another embodiment, the dock leveler further includes a roller member mounted to an end of the intermediate member, and the step of moving the intermediate member includes the step of rotating the roller member.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.